Functional significance of dauciform roots: exudation of carboxylates and acid phosphatase under phosphorus deficiency in Caustis blakei (Cyperaceae)

Playsted, C. .W S., Johnston, M. E., Ramage, C. M., Edwards, D. G., Cawthray, G. R. and Lambers, H. (2006) Functional significance of dauciform roots: exudation of carboxylates and acid phosphatase under phosphorus deficiency in Caustis blakei (Cyperaceae). New Phytologist, 170 3: 491-500. doi:10.1111/j.1469-8137.2006.01697.x


Author Playsted, C. .W S.
Johnston, M. E.
Ramage, C. M.
Edwards, D. G.
Cawthray, G. R.
Lambers, H.
Title Functional significance of dauciform roots: exudation of carboxylates and acid phosphatase under phosphorus deficiency in Caustis blakei (Cyperaceae)
Journal name New Phytologist   Check publisher's open access policy
ISSN 0028-646X
Publication date 2006
Sub-type Article (original research)
DOI 10.1111/j.1469-8137.2006.01697.x
Volume 170
Issue 3
Start page 491
End page 500
Total pages 10
Place of publication Oxford
Publisher Blackwell Publishing
Collection year 2006
Language eng
Subject C1
300302 Plant Growth and Development
620209 Ornamentals, Australian natives and nursery plants
06 Biological Sciences
0605 Microbiology
0607 Plant Biology
Abstract Caustis blakei produces an intriguing morphological adaptation by inducing dauciform roots in response to phosphorus (P) deficiency. We tested the hypothesis that these hairy, swollen lateral roots play a similar role to cluster roots in the exudation of organic chelators and ectoenzymes known to aid the chemical mobilization of sparingly available soil nutrients, such as P. Dauciform-root development and exudate composition (carboxylates and acid phosphatase activity) were analysed in C. blakei plants grown in nutrient solution under P-starved conditions. The distribution of dauciform roots in the field was determined in relation to soil profile depth and matrix. The percentage of dauciform roots of the entire root mass was greatest at the lowest P concentration ([P]) in solution, and was suppressed with increasing solution [P], while in the field dauciform roots were predominately located in the upper soil horizons, and decreased with increasing soil depth. Citrate was the major carboxylate released in an exudative burst from mature dauciform roots, which also produced elevated levels of acid phosphatase activity. Malonate was the dominant internal carboxylate present, with the highest concentration in young dauciform roots. The high concentration of carboxylates and phosphatases released from dauciform roots, combined with their prolific distribution in the organic surface layer of nutrient-impoverished soils, provides an ecophysiological advantage for enhancing nutrient acquisition.
Keyword Acid Phosphatase
Citrate
Cyperaceae
Dauciform Roots
Malonate
Organic Acids
Phosphorus Deficiency
Phosphorus Uptake
Plant Sciences
Atp-citrate Lyase
Lupinus-albus L.
Cluster Roots
Western-australia
Organic-acids
White Lupin
Proteoid Roots
Lateral Roots
Soil
Metabolism
Q-Index Code C1

 
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Created: Wed, 15 Aug 2007, 08:46:57 EST